Real-Time Digital Timing in Positron Emission Tomography

Abstract

Abstract-Positron emission tomography (PET) requires accurate timing of scintillation events to properly discriminate between coincident and noncoincident pairs. The traditional solution to timing is based on custom application specific integrated circuits (ASIC) designs, whose cost may not be justified in the design of experimental small animal PET scanners. The new generation of PET scanners introduces the idea of continuous sampling of the detected scintillation pulse, replacing event-triggered acquisition front-ends. This approach enables new options to the timing procedure based on digital processing of the sampled pulse signal. This work proposes a time stamping algorithm based on the optically matched filter and compares the potential performance benefits of this approach versus other FIR-based timing algorithms, some of which have been already implemented by different authors. Results show that the coincidence timing resolution may be as low as 1.5 ns without the need of expensive high-speed converters when the proper signal processing is applied.

PET System Synchronization and Timing Resolution Using High-Speed Data Links

“…Advances in timing algorithms and especially increases in ADC sampling rates allow tighter shapings to be applied to trigger signals so that pile-up and event time uncertainty are reduced. With FWHM coincidence resolutions below 2 ns [17] and expected to improve significantly [18], the effect of mis-synchronization between DAQ boards becomes increasingly important, since any discrepancy between reference times on acquisition FPGAs is directly reflected on the measured difference between timestamps from potentially coincident events. Hence, synchronization errors on the order of 500 ps already have a non-trivial effect on the measured timing resolution figures.…”

Digitizing data acquisition and time-of-flight pulse processing for ToF-ERDA

“…Digital timing for positron emission tomography and nuclear physics experiments using multiple scintillation detectors is already established [6,7]. Digitizers have also been used successfully in extracting high-resolution timing information from silicon detectors [8].…”

Estudio e implementación de algoritmos digitales para la mejora de la resolución temporal en sistemas de tomografía por emisión de positrones

“…Otros estudios proponen el uso de versiones digitales de LE [13,14,15]. Porúltimo, cabe notar la existencia de grupos de investigación que proponen discriminadores digitales que no están basados en discriminadores analógicos [10,16].…”

“…No se han encontrado trabajos donde se hiciera un estudio analítico de los efectos en la resolución temporal de la frecuencia de muestreo. En algún trabajo, sí que estudian de forma experimental o mediante simulaciones el efecto de la frecuencia de muestreo [16,111].…”

“…Estos métodos funcionan en tiempo real a medida que las señales son adquiridas. Guerra et al [16] proponen diferentes algoritmos, entre los que se incluyen la interpolación lineal, DCFD, un filtro adaptado clásico (que usualmente es considerado elóptimo en la presencia de ruido aditivo) y un filtro adaptadoóptico (que está pensado para ruido de Poisson típico de detectores de partículas). En su trabajo, proporcionan detalles de la implementación hardware de los algoritmos de extracción del tiempo del pulso recibido, como parte de un PET para animales pequeños [136].…”